Produção de forragem, teor de nitrogênio e eficiência de uso do N em cultivares de aveia certificadas e salva

Abstract

The use of cultivated pastures during the winter period has become a constant practice in the daily life of rural producers, demonstrating its benefits when integrated into integrated agro-livestock production systems (SIPAs). Oats (Avena sativa) are a widely used forage crop in this system, and the production of high-quality forage is essential to meet the demands of the crop-livestock system, ensuring animal performance and quality production. An experiment was conducted on a rural property in Vitorino - PR, from April to October 2022, to evaluate different types of forage oats, including certified seeds (BAGUAL, BRS 139, and AF1340) and a variety saved by the farmer. The experimental design used was completely randomized, with four replications. Animals were introduced for grazing when the oats reached a height of 20 to 30 cm, with the goal of maintaining an average pasture height of 15 cm. Brangus cattle were used, and the method of continuous stocking grazing with a variable stocking rate was adopted. Over different time periods (Period 1: 06/13-07/13; Period 2: 07/13-08/10; Period 3: 08/10-09/08; Period 4: 09/08-10/05), the following variables were evaluated: dry forage matter, tiller population density (TPD), leaf/stem ratio (L/S), forage density (FD), and nitrogen content in plants. Boxplots were used to analyze and interpret the variables over time. Nitrogen levels in the grazed area and in cages varied between collection dates but were very similar on the same date. The highest correlations of nitrogen levels in plants (whether in cages or pasture) occurred with the leaf/stem ratio and Tiller Population Density (TPD) variables. The nitrogen supply was not sufficient for the forage oat cultivars, indicating limiting values for pasture development. However, all cultivars reached their maximum productivity potential. The oat cultivar from saved seeds exhibited similar behavior regarding nitrogen concentration and accumulated dry matter production in both cages and the grazed area. However, in cages, the nitrogen concentration of this cultivar was lower than the others.